Emerson ControlWave Instruction Manual page 24

ControlWave I/O Expansion Rack Instruction Manual
Power
Supply
WARNING Do not perform "hot swapping" in a Class I, Division 2 hazardous
Hot Swap of I/O
Modules
Hot Swapping of
Power Supplies
Watchdog
Switch
2-12
The PSSM provides your ControlWave with dual power supplies for
operational redundancy.
You can optionally purchase the PSSM with only a single power
Note:
supply installed, however, this configuration does not allow for
redundancy within the PSSM which is discussed throughout this
section.
The PSSM includes two independent power supplies. Should either
power supply fail, operations automatically continue using the second
supply, and you can "hot-swap" the failed power supply with a spare
unit without interrupting control operations. The PSSM also supports
hot swapping of I/O modules. However, you cannot replace the entire
PSSM itself without first turning off power to the ControlWave.
When used as part of a redundant system, the failure of one of the two
power supplies in a redundant power supply sequencer module would
not force a failover to the other controller. Only the loss of both power
supplies on the redundant power supply sequencer module would
trigger a failover.
The PSSM ships from the factory configured for a nominal input supply
of 24Vdc.
location.
The PSSM supports "hot swapping" of I/O modules. This means you
can insert or remove an I/O module from the chassis while power is
live.
There is no support for "hot swapping" of the entire PSSM itself, or the
CPU module, however, if you have the dual power supply version, you
can hot swap a power supply on the PSSM. For information on hot
swapping of power supplies see Section 2.3.6.
PSSMs include a watchdog metal oxide semiconductor field-effect
transistor (MOSFET) switch connector. The purpose of the watchdog
connector is to trigger an external alarm or annunciator if the
ControlWave enters a "watchdog" condition in which the CPU cannot
control your process. This occurs on power-up before the ControlWave
project starts, if the unit is reset, if the ControlWave project "crashes"
or if the system loses power. See Section 2.3.7.
Installation Revised Aug-2015